1.a) Field of the Invention
This invention relates to a set of instruments for reaming out dental root canals, each comprising a conical stem provided with at least a helicoidal cutting lip, and ending in a portion without said lip. The set furthermore comprises instruments the end diameters of which, that is to say the diameters measured at the roots of the end portions, are different from each other.
2.b) Description of the Prior Art
Such sets of instruments, constituted by reamers or files, are known per se.
The instrument sets are made in a series of different end diameters situated, most generally, between 0.06 mm and 1.4 mm. In these instruments, the conicity of the stem is constant, whatever the end diameter may be, this conicity being expressed, generally, not by the included angle, but by the difference between the end diameter and the diameter measured at the root of the helicoidal cutting lip or lips. The length of the portion of the stem provided with the said lip or lips being generally 16 mm, the difference between the end diameter and the diameter of the stem at the root of the lips is most generally about 0.32 mm.
The practitioner who executes reaming out of a dental root canal uses the instruments of the set, commencing with an instrument of small diameter and continuing, successively, with the instruments of increasing diameter until the whole infected dental pulp is eliminated and the canal reamed out has a shape suitable for its sealing by means of stopping with gutta-percha or cement.
The up to date odontological techniques instruct that the root canal should be given a more wide-mouthed shape than previously, the canal being large at its cervical portion near the crown of the tooth and remaining very narrow at its apical portion in the vicinity of the end of the dental root. As a matter of fact, this very wide-mouthed shape of the root canals after reaming out is more suitable for stopping by means of gutta-percha, a technique which is being used more and more.